Illustrations in essays?

Can anyone assist me?
I am writing an essay about classical mechanics and an extension into thermo dynamics and ideal gas laws as part of an engineering course
Is it appropriate to draw illustrations to explain further and/or accompany your explanation of the example: Internal energy gas to show how the particles collide etc
I'm always trying to achieve a distinction and some have explained how illustrations have helped them achieve top marks in their essays.
Opinions, please?

Yes, some people learn not only by reading an essay but also by seeing the mechanics behind it-as evidenced in some scientific journals. To reference-one can say Internal energy gas does (blank) with particles to collide as seen in diagram/illustration A/1 etc.
Illustrations should be crafted by yourself or properly sourced in your document when using them based on the sourcing that your essay is required to take after. As someone who understands things more with illustrations/graphs/data represented in a different way-it's refreshing and will also be to your professor as it's something else to focus on.